Digital signaling decouples activation probability and population heterogeneity

Area of Science:

• Cellular signaling and systems biology
• Molecular and cellular biology
• Biophysics

Background:

• Digital signaling enhances cellular decision-making robustness in noisy environments.
• The transmission of temporal information by digital systems, particularly in cellular contexts, remains poorly understood.
• The NF-κB signaling pathway is a critical digital system involved in cellular responses to stimuli.

Purpose of the Study:

• To elucidate how temporal input information is encoded and decoded by the NF-κB system.
• To investigate the relationship between stimulus characteristics (dose, duration, temporal profile) and NF-κB pathway dynamics.
• To understand how these dynamics influence gene regulation and cellular phenotypes.

Main Methods:

• Utilized mathematical modeling to predict NF-κB system behavior.
• Employed microfluidic single-cell experiments to validate model predictions and observe cellular responses.
• Analyzed transcription factor dynamics and gene expression under varying inflammatory input profiles.

Main Results:

• The integral of the stimulus (concentration × duration) determines the fraction of cells activating NF-κB.
• The temporal profile of the stimulus dictates NF-κB dynamics, cell-to-cell variability, and gene expression outcomes.
• Sustained, weak stimulation resulted in heterogeneous, delayed activation and gene expression, while transient, strong stimulation led to rapid, uniform dynamics.

Conclusions:

• Digital NF-κB signaling provides multidimensional control over cellular phenotypes.
• The system independently regulates single-cell activation probability and population heterogeneity.
• Input profile allows for parallel and independent control of cellular responses, enhancing adaptability in noisy environments.